feat(phase131): LLVM backend re-enable & PHI ordering bug discovery

Phase 131: JoinIR → LLVM individual fixes (minimal scope)

## Modifications

### 1. LLVM Backend Re-enable ✅
- Built with --features llvm to enable real LLVM execution
- Verified Python/llvmlite environment (llvmlite 0.45.1)
- Fixed llvmlite deprecated API: removed llvm.initialize() call
- Successfully moved from Mock backend to real LLVM harness execution

### 2. PHI Instruction Ordering Bug Discovery ⚠️
- Discovered critical bug: PHI nodes placed AFTER terminator instructions
- LLVM IR constraint: PHI must be at block start, before any non-PHI
- Root cause: finalize_phis() in llvm_builder.py emits PHIs after block termination
- Affects all 6 tests with control flow merges

### 3. ConsoleBox LLVM Integration ⚠️
- Confirmed ConsoleBox not registered in Rust VM environment
- Deferred to Phase 132 (prerequisite issue)

## Results

Modified files:
- src/llvm_py/llvm_builder.py: Removed deprecated llvm.initialize()
- docs/development/current/main/phase130_joinir_llvm_baseline.md: Added Phase 131 results
- CURRENT_TASK.md: Added Phase 131 completion report

Test results:
- ✅ peek_expr_block.hako: LLVM execution success (Result: 1)
- ❌ 6/7 tests: PHI ordering bug (requires Phase 132 refactoring)

## Success Criteria

- ✅ LLVM backend minimal re-enable (1/7 test passing)
- ⚠️ PHI ordering bug discovered and documented
- ⚠️ ConsoleBox integration deferred to Phase 132

## Phase 132 Handoff

Priority 1: Fix PHI instruction ordering bug (finalize_phis() refactoring)
Priority 2: Resolve ConsoleBox registration issue
Priority 3: Enable remaining test cases for LLVM

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/llvm_py/llvm_builder.py

@@ -89,8 +89,8 @@ class NyashLLVMBuilder:
     """Main LLVM IR builder for Nyash MIR"""
     
     def __init__(self):
-        # Initialize LLVM
-        llvm.initialize()
+        # Initialize LLVM (llvm.initialize() is deprecated in newer llvmlite)
+        # llvm.initialize()  # Removed - now handled automatically
         llvm.initialize_native_target()
         llvm.initialize_native_asmprinter()